Manual telephone system



Sept 1927' w. T. POWELL 1641'235 MANUAL TELEPHONE SYSTEM Filed July 28, 1924, t 1

v E; I I I I H INVENTOR WlNFRE-D T. POWEL BY Ma,

' ATTORNEY Se t. e 1927. p w. T. POWELL MANUAL TELEPHONE! SYSTEM w ZOEwOu ATTORNEY INVENTOR WINF'REZD T. POWELL.

3 Sheets-Sheet 2 WZOFEWE JJ 01F ZOZZOU Filed July 28 M ZOEMOK T MQLLO Sept. 6 1927.

W. T. POWELL MANUAL TELEPHONE SYSTEM Filed July 28, 1924 3 Sheets-Sheet 3 mm om w 0.

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N MQWEQ UZOILMJME. @MDPKQUKO AM INVENTOR WINFREDT POWELL 7 BY W ATTORNEY Patented Sept. 6, 1927.

UNITED STATES 1,641,235 PATENT OFFICE.

WINFBED T. POWELL, OF ROCHESTER, NEW YORK, ASSIGNGR TO THE STROMBERG' CARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCHESTER, NEW YORK,

A CORPORATION OF NEW YORK.

. MANUAL. TELEPHONE SYSTEM.

Application filed Ju1y'28, 1924. SeriaiNo. 728,555.

This invention relates to telephone. systems and more particularly to telephone systems having one or more oiiices. In such telephone systems it has been customary to provide io-called order wires interconnecting the various oflices through which an operator at an originating oiiice transmits the wanted number to a B operator at a distant otiice and over which this last named operator in turn assigns a trunk for the use of the A operator in extending a call.. Such order wire operation has proved to be'especially ineliicient during busy periods and has resulted in numerous wrong connections.

. It is the purpose of the present invention to provide an improved arrangement whereby separate order wires may be dispensed with to the end that the operation of a multioliice system may be greatly facilitated and the number of incorrect connections reduced to a minimum.

One oi? the features of the present invention resides in the provision or means Whereby an operator at the originating office may auton'iatically select an idle trunk to an operators position at a distant otlice and whereby the designation of the trunk so selected is indicated to the operator at the originating ofiice.

Another feature of the invention consists of the arrangement whereby an operators telephone set is automatically connected to a cord circuit and then subsequently automatically disconnected from the cord circuit and connected to an idle trunk leading to an operators position at a distant wanted ofiice.

A further feature of the invention includes the arrangement whereby a trunk extending between two ofiices, may take the place or an order wire, p

The drawings with Figs. 1, 2 and 3 arranged in the order named, diagrammatically represent a portion. of a telephone system including the present invention- Fig. 1 represents a telephone line and an A'oper ators cord circuit of an originating exchange or ofiice. Fig. 2 represents a portion of a trunk circuit leading to a distant oflice and also shows several groups of relays by which such an idle trunk leading to a wanted oiiice is selected. Fig. 3 represents the remainder of said trunk which tern'iinates in a manual connecting plug at aB operators position in the wanted oiiice. At the extreme right of Fig. 3th'ere is indicateda telephone line which is referred to as a called'telephone line. I

For purposes of this description it is assumed that one hundred trunks extend between oiiice Number 1 and oiiic'e Number 2, but in practice this number is dependent on the tra'tfic. Although the showing of the trunk selecting arrangement is very much abbreviated, it will be understood't-hat at each operators posit-ion there are provided ten of the multi-contactrelays similar to relay 52 and that ten other relays similar t-o relay 55, are also provided at each position. It will also be noted that each trunk is'multipled to contacts of a multi-contact relay at each operators position. This will appear by tracing the multiple connections from the conductors 62 and 66. A similar group of trunks leading to each oflice is accessible ,to eaclroperators position'and a single office key similar to appearing in the lower left hand corner of Fig. is provided at each operators position for each or the various oi fices accessible to that position.

It is believed that the invention'will best be understood by describing the method of extending a telephone connection from a subscribers substation indicated'at A, to a subscribers substation whose telephone line terminates at a distant oiiice.

i/Vhen the subscriber at A removes his receiver from its switch-hook, the line relay 5 is energized in. the well known manner over the two sides of the calling line in series and thereby lights the line lamp The operator whose cord circuit is shown in Fig. 1 then inserts the answering plug 7 of this cord circuit into the jack 8 of the calling line. This operation is effectiveto energiZe the cut-ofi relay 9 and the operators bar relay 10 in a circuit extending from grounded battery, through the right hand high resistance winding of relay lOQthrOugh the sleeve contacts of the plug 7 and jack 8, and winding of the cut-off relay 9 to ground. As soon as the cut-0E relay 9 is actuated it opens the energizing circuit of the line relay 5, which relay deenergizes and opens the circuit of the lamp 6 to extinguish it. The operators bar relay 10 when operated, closes a lockingcircuit for itself through its low resistance left hand'winding and through its left hand armature and front contact (ill (iii

over the remainder of the circuit previously described. is is Well known, the high re sistance and low res'stancc windings ol' the relay l are provided to prevent a second operator-s telephone set from being; connected to a calling; subscribefs line at the same time. in the o ert that two opershould sinndtaneously connect the answering ends oi their cord circuits to the same calling; line.

lr'hcn the relay is operated it closes a circuit from ground. its outer right hand armature and :tront contact. uppermost armature and back contact of rehy 11, Winding ol" the slow releasing relay 1E5, winding of the relay 13, left hand nding ol the relay ll. winding ol the l. h r a e relay 15, to grounded batten The ance of the relay is such (5000 ohms for example) that it is operated in this circuit. but the other n'ientioned relays in series therewith, are not operated at this time. With the relay 15 operated. an eucri' circuit is closed from grounded ha right hand Winding of the relay l-l. coiitact and armature of relay to. to g ound. hen the relay 1% thus energized. it c: tends a circuit from grounded battery. its front contact, armature and left hand Winding, and thence through the \i'inding's oi relays 13 and 12, over the remainder oil the circiiit previously described as extending to ground at the righthand 'lront contact and armature of relay 10. Relays 12 and 13 are energized in this last circuit. ltelay 13 closes a break-point in the operating circuit oil the meter is and with the relay 1L1 resistenergized the operator's cut-in relay .18 is energized from grounded battery Winding of relay 18, front contacts and armatures otrelay l2, conriluctor 19. and the u'ini'lingr of relay 1T, to ground. The relay 18 is thereby energized and at its left hand armatures and front contacts. extends the opera tor's telephone set through the conductors 59. ca 520 and 21 over the answering end of the cord circuit in use, to the calling subscriber-s line. The relay 1? is energized in series with the relay 18 and closes the remaining brealtpoint in the circuit of the meter 16. easing; the same to operate. The operation of relay 1? short circuits and releases relay fl-l. which opens the circuit of the meter allowing it to release al'tcr making a record that the operator has answered one call.

The relays 13. ll. .15. '1? and the ill)" pedance coil 92, are common to an operators position and are provided to permit the operator to start a second call through a second cord circuit While she is complctiiur the connection on a first cord circuit such as that shown in Fig. 1. This arrangement llitl'l'llllt-l the operator to plug up" a second call while she is pressing the ringing hey to apply ringing current over a first cord circuit. The arrangement of relays is such that only two calls may he in the process of conniletion by one operator at the same time. If the operator plugs up more than two calls bc'lore any one connection is complctcd, then all of these calls will tail.

From the preceding; description it will he seen that the operatol". telephone act. is connected to the cord circuit. by the operation of relay 1.8.and that this relay is contr llczl by relay 1?. lVhcn one call is anrelay in will operate as above doan 1. scrihcd and will he released when relay 1.1

is energized, after the completion ol the c nneetii n. as will be later described. Alier the completion of a first crmnection. a second ansnering cord similar to 1' is inscrtciil in an answering jack. The relay 10 at the second cord operates. but relay 1?. at this second cord cannot operate. because ol the shunt path to ground through coil 2-2. which has been placed in the connnon o iicrating circuit o't relay 122 by the operation ol rela 17. This shunt path does not prevent relay 12 'l'roni holding when once operated, but it doe prevent it from operating. ll' hen the re; stances o'li relays 12. 13, ll, 15 and coil 22 are properly chosen, the above operaticn is obtained without the use of marginal relays or special adjustments. When the lirst connection is completed, the circuit of relay 12 associated with this connection is opened and it (lecnergizes. :lelay 12 of the second connection now immediately operates. because the above described shunt path is removed when relay 1? releases at the completion of the first connection. These rcr'sistance values are such. however, that it more than one call is phiggcd up while another in the process of completion, the additional shunt path to ground through the additional relay 12 will prevent the operation of either.

As soon as the operatoi."s telephone set. which is iinliratcd at the lower part of Fig. i. is connected to the falling; telephone line through the answering end oi" the cord circuit. the operator inquires for the number of the Wanted telephone line. On asccrtainiin that the wanted line terminates at a distant oliice the operator depresses the single o'll'icc he 50, which is individual to thenanted oiiicc. The operation ol' key closes a circuit from grounded battery over conductor Iii. Wl'llzildEI ot' the lllllllht'filllilltlii relay 52, its continuity sprint and baclc contact, innermost hack conta t and armature ol rcla 53. to ground. llelay 52 is thus energized and (hires a locking circuit for itself from grounded battery, at lcey fill. winding of relay 52 its continuity spring}; and innermost armature. Winding of relay 5i, to ground. The clor ire of this circuit energizes relay 5!- whieh its left. hand armatures and trout contacts closes l'n'calepcnnts in the operations telephone circuit. ll 'ith the group relay 52 Itill iii battery, winding of this relay, its Continuity spring and back contact, conductor 56, innermost left hand front contact and armature of relay 52, conductor 57, uppermost back contact and armature of relay 58, to ground. "With relays 52 and 55' actuated the operators telephone set is connected to the selected idle trunk over conductor 59, outer armature and front contact of relay 54L, armatureand contact of relay 55, contact v61v and armature of relay 52, conductor 62 to conductor'63 of the selected trunk, thence through the lower side of the repeating coil of Fig. 3, through both windings in series of rela 64, u er left,

y lip hand winding of the repeating CO1 trunk conductor 65, conductor 66, armatureand contact 67 of relay 52, front contact and armature 68 of relay 55, innermost front contact and armature of relay 54, conductor 69 to the other side of the operators telephone set. I The impedance coil 95 is bridged to this circuit so that the relay 64 is energized in this circuit to effect the operation of the slow releasing relay 70 from grounded 7 battery, winding of this relay, front contact and armature of relay 6,4, to ground. This causes the supervisory lamp 71 to be lighted in a circuit from grounded battery, the lamp 71, armatures and back contacts of relays 7 5 and 72, innermost front contact and armature of relay 70, outer back contact and armature of relay 7 3 to ground.

At this time a tone is transmitted to the A operators set from the source of tone current, outermost back contact and armature of relay 72, armature and back contact 7 4c of relay 75, left hand front contact and armature of relay70, right handwinding of relay 73 and thence through the condenser and left hand winding of relay 73, to grounded l A tone current is then' induced battery. through the trunk including the conductors 63. and and'thence to the A operators telephone set. This tone is heard in the A operators receiver until the trunk, whose conductors are designated 63 and 65, is inductively connected to the B operators tele- Only one trunk at a B operators position can be connected to theoperators circuit at one time and when this takes place the tone is dis-.

connected from the A operators telephone. The disconnection of the tone is an indication to the A operator to repeat the wanted number without being challenged by the B operator.

As soon as the relay 75 is operated as Will later be described. the supervisory lamp 71 is intermittently lighted in a circuit from grounded battery, lamp 71, right hand armature and front contact of relay 75 and the flashing interrupterto ground. Under the control of this circuit the supervisory lamp 7l flashes and when the B-operator receives the wanted number, she announces the number of the flashing lamp, which assigns to the A operator the trunk to be used in completing the connection.

It willthus be seen that it is not necessary for the B operator to choose a trunk out of a particular group leading to the originating ofiice. The trunk is automatically selected and the flashing of its supervisoryv lamp is an indication as to which trunk has been selected. It may be well to mention at this point that the wiring of the 13 operators cut-in circuit for three trunks is shown in Fig. '3, together with the common circuit arrangement for preventing more than one trunk from being connected to the B opera-3 tors circuit at one time. It will be understood that all of the trunks at this position are wired in the same way as those shown in this figure. hen a trunk is chosen at the originating end its relay 70 is energized and if no other'trunk at the B position is connected to the operators telephone circuit, the relay 7.5 is operated from grounded bat tery, retea'se key 78, back contact and armature of relay 79, right hand winding of relay 75, outer armature and back contact of relay 72, continuity spring and armature of relay 70, ground. Relay when operated closes a locking circuit for itself from grounded battery, release key 78, winding of relay 79, left hand winding, front contact and armature of relay 75, armature and front contact of relay 70, back contact and armature of relay 72,- to ground. Relay 79 upon operation opens all the energizing circuits to all of the relays corresponding to 75 at this po sition, so that the operation of a relay corrcsponding to 70 of another-trunk circuit cannot result in the connection of a. second trunk to this 13 operators telephone set.

From the foregoing description it will be understood that the supevisory lamp 71 is lighted steadily, as soon as the trunk is 2111- tomatically selected, but is caused to flash intermittently as soon as the operators tele phone set is connected to this selected trunk.

The series circuit extending from ground through the continuity spring 80 insures that only one trunk can be connected to the operators telephone circuit when a call is plugged up, even though several are waiting an operators attention. The lock-out circuit controlled by the relay 79 insures that a call on a'wtrunk near the ground end of the series Will not cut-in and release one trunir fi l to the selected trunk results in the operation of the slow releasing;- rela'y 529 in a circuit extending; l'roin tll'OlllldQt'l battery, windingof this relay, heel: contact and continuity spring of relay ll, sleeve contacts of the plug 52? and the jack 7?, resistance. to ground. The depression oi the ringing key 26 etlects the operation of relay Q8 and the actuation of this relay completes a circuit from around. rin ht hand a'riuaturi and front contact. ot relay 2S, inner armature and front contact of relay Qt), upper winding, of relay 11, to orouruled battery. This results in the enerp nation of relay ll. wl'iereby this relay is loclced operated from grounded battery, throupjh its lower winding. lowermost armacontinuity spring; to groan-cl ture and through the sleeve contacts oi the plug 23 and the jacl; ii. The operation of the relay it also closes a break-po nt in the calling): end at the cord circuit. The operation oi relay 28 also closes a circuit FY0211 around. left hand 'lront contact and armature. outer armature and front contact of relay 29. winding of relay 330. to ground. The ringing re" by 32 is also ei'iergrized at this time in a circuit from erounded. battery. resistance, winding; of this relay, right hand arnunnrc and hack contact oit relay 23kt inner front contact of relay E29 and thence to around at the armature and front contact of relay Although ringing current is selected at the position. in order to render the operation the same as in the case oi a local call. the ringing current is innnediately tripped as will hereina'tter he described.

he soon as the calling; plug; 23 is placed in the. jack T7 ol the aesigrned trunk, a circuit is closed from ground at the lower armature and back contact of relay Ell. winding of the slow releasing relay 82 through the ring contacts of the jack TT and plug 2; inner .rnosl armature and trout contact of the ringing: relay 3:3, winding of the trip relay 38, right hand armature and back contact of relay iltl. inner armature and heel: contact ol? relay I37 and thence to the source of ringingr current. This circuitis etlectire to enso the trip relay 233% which relay at its armature and trout contact; places a short cir uit about the ringing relay 3:2. This laat nained relay is thereupon deenergized to render the conductors of the cord circuit cont inuons. it ill thus be seen that as soon as the jilllp 23 is cijinnected to an outgoing lrnnle. riir my; current is disconnected from the cord circuit.

ltclay i on operating closes a circuit for relay ill through the upper winding of this last nanicd relay. armature and front contact oli relay S12, armature and bacl: contact ol relay 32. lelt hand winding of relay 31, to grounded battery. Relay S'l when open ated opens the circuit of relay and closes a locking circuit for itself through its lower winding, inner front contact and arn'iature, sleeve contacts of the jack Ti" and plug 523, continuity spring. armature and lower wind in g of relay 1], to grounded hatter-y. Relay S1 at its l()\\l1110rlt-zllllltttlllf and trout con tact closes an operating circuit tor the relay 58, which relay maintains this trunk unselectable as long as the plug 23 is in the. jttCl-I T7.

The l3 operator alter recci \i no the designation of the wanted telephone line inserts the callin plug 83 into a multiple jack tlil. o't this wanted line and dcprcwes a ringing hey such as 85. This operates the relay 86. which in turn closes an operating circuit For the relay 137 from grounded battery, its left hand winding. inner armature and trout contzmt of relay 8r outer lront contact and armature of relay Sti to ground. Also when relay S6 is operated it eli'ects the energization of the relay 7: in a circuit t'aceable from grauinded battery, left hand winding oi relay T2, inner leiit hand trout contact and armature ot relay 88, inner front contact and armature of relay 86, to ground through the winding of relay ill. The energization ot relay 72 at its arn'iature 9t opens the incl-ling circuit ter- 8 o mratous telephone set hecoines accessible to any of the other trunks. Relay 8'? on operation clos a locking circuit for itselt through its left hand winding, left hand front contact and armature. conductor 85,) inner armature and hacl; contact of relay 73, outer 'l'ront contact and armature of relay T2, to ground. At this time the ringing); relay is also opefated from grounded battery. ik (lance, winding ot the relay 90, inner front contact and armature of relay frltl, inner trout contact and arlnz-iture of relay oli. winding oil? the relay Ell, to ground. Ringing current is supplied to the called line from the ll) cycle source of current, innerinost trout contact and armature oil relay 81', back contact and armature of relay 92, outer itront contact and aru'iature ol? relay TO, winding: ol the trip relay Eli). inner trout contact and armature ot relay JO, ring con tacts ot' the plug 83 and jacl: 84: through the wanted substation circuit on the party line, tip contacts ol the jack ill and plug 83. and thence to ground. Under the coin trol of this circuit ringing; currei'it is sup plied to the ringer at the wanted aubstation until the wanted party answers-1, at which time the trip relay 9-) is energized to short circuit the ringing; relay J0. and disconnect ringing current. When the called party answers the supervisory relay Til operates and at its left hand armature and 't'ront contact places a shunt circuit about; the high resistance winding of relay ti l. This operation is cll'ectire to cause the en ergizaation of the siuperrisory relay 231, shown near the right of Fig. .1.

the relay To, so that the' til) Ill!

At the close of the conversation, when the subscriber at B replaces his receiver onits switchhook, the supervisory relay 73 deenergizes and opens the short circuit about the high resistance winding of relay ea. The inclusion of this high resistance winding in series with the trunk conductors 63 and 65, results .in the deenergization of the supervisory relay 31 at the Aoperators position, shown in l. The deenergization of the supervisory rela Slfot Fig. 1 closes a circuit for" lighting tie supervisory lamp l6, which circuit is completed from grounded battery, lamp 46, back contact and middle armature of relay 82, outer back contact and armature of relay 31, inner armature and front contact of relay 11, to ground. The disconnect lamp 7.1 of the B operators position is also lighted in a circuit closed from grounded battery, lamp 71, armature and back contact of relay 75, armature and back contact of relay 72, innermost right hand front contact and armature of relay 70, back contact andarmature of relay 78, to ground. The lighting of the lamp 71 at this time is a signal to the B operator to remove the plug 83 from the jack 84 of the called line. Also when the calling party replaces his receiver on its switchhook, the supervisory relay 39 deenergizes to light the answering supervisory lamp ll in a circuit from grounded battery, lamp 41, inner armature and back contact of relay 39, inner armature and front contact of relay 10, winding ot the impedance coil 45, to ground. The llghting of lamps ll and 46 is a signal to the Aop erator to disconnect plugs 7 and 23. I

For the purpose of allotting an idle trunk for use, a relay such as 58 is energized as soon as atrunk is seized. It has been assumed that one hundred trunks are provided between the offices Number 1 and Number 2. These one hundred trunks are divided into ten groups of ten each and a group relay such as 53 is providedindividual to each group. When all of the trunks of. a group are in'use the relays such as 585 and 58 associated therewith are'held energized, so that the group relay 53 is actuated to assign another group of trunks for use. Under such conditions when an operator depresses an oflice key, the multi-contact relaysuch as 52 is operated, so that an idle trunk from another group is selected.

It will thus be seen that novel means are provided for connecting the operators telephone setthrough several difierent portions of a telephone connection and for obviating the use of a separate order wire between operators positions.

What I claim is: 1 In a telephone system, an A-ope'rators position a B .oper'ators position, telephone lines terminating at each of said positions,

a was between said positions,

l g-nation of means for selecting said trunk. for use, a

means for connecting said trunk to a wanted telephone line terminating at said B operators position. I 2. In a telephone system, an A operators position, a B operators position, telephone lines terminating at each of .said positions, a plurality of trunks serving to interconnect said A and B operators positions, an operators telephone set at each of said A and B operators positions, means for selecting a trunk for use, a cord circuit for interconnecting a calling telephone line at the A operators position with any of said trunks, means responsive to the connection of said cord circuit to a calling telephone line for connecting said A operators telephone set thereto, means responsive to the selection of an idle one of said trunks for connecting said B operators telephone set thereto and for disconnecting said A operators set from the calling telephone line and for connecting it to the selected trunk whereby said A and B operators may converse thereover, means for connecting the calling telephone line to the selected trunk'through said cord circuit, and other means for connecting the selected trunk to a wanted telephone line.

3. In a telephone system an A operators position, a B ope'rators position, telephone lines terminating at each of said positions, trunk lines extending between said positions, an operators telephone set at said A operators position, an operators telephone set at said B operators position, a cord circuit connectible to a calling telephone line, means operating on connection of said calling telephone line to said cord circuit for extending said A operators telephone set thereto, means including a plurality of relays for selecting an idle one of said trunks, means including an oflice key at said A operators position for co'ntrollingsaid relays, means responsive to such selection for indicating at said B operators position the designation of theselected trunk, means responsive to said selection for disconnecting said A operators telephone set from said callingtelephone line and for interconnecting said A operators telephone set and said B operators telephone set over the selected trunk whereby the B operator may report the dies the selected trunk to the A crater, for eennecting said card sir lac cult to the selected trunk, and means for c iinnecting the selected trunk to the noted telephone line.

at. in a telephone system, an A operators position, a B operators position, telephone lines terminating at said it operators position, party telephone lines terminating at said it operatofis position, an operatous telephone set at each oi said positions, a plurality of trunks for interconnecting said positions, a phirality oi? sources of signaling current at said ll operators position for selectively ialing stations on the party lines terminating thereat, a single ringing hey connnon to said plurality of trunks for each source of ringing current, a cord circuit at said A operator-s position, nianual means for extending said cord circuit to a telephone line on the initiation of a call thereover, means responsive to said extension for connecting said A oporatofs telephone set to said cord circuit, means controlled from said A operators position for autoniatically selecting an idle trunk terminating at a ll operator's position, means operating responsive to said selection for disconnecting aid operators telephone set from said cord circuitand for connecting it to said selected trunh', other means responsive to the selection of said trunk for connecting said ll opcratous teleohono set to said selected trunk whereby said A operators telephone set and said l3 opcrators telephone set are tclephonica ly connected together, means for connecting the cord circuit to the selected trunk, means for connecting said trunk to the wanted telephone line, means responsive to the connection of said trunk to the Wanted telephone line for placing said single set oi keys in operative relation to the selected trunk to the exclusion of the other trunks, moans controlled by one of said con'inion hers t'or selectively applying ringing current to the wanted telephone line, and means controlled over said Wanted telephone line for disconnecting said signaling current.

5. In a telephone system, an A operators pos' ion, a ll operator's position, telephone lines terminating at each of said positions. certain ol :aid telephone lines hcing party lines. an operalons telephone set at each of said positionsg a plurality oi trunks tor interconnmrting said positions, a plurality of sources of signaling current at said B operatons position for selectively signaling stations on the party lines terminating thereal. a. single ringing key common to said tiluralitr ot' trunks for each source of ringing current. a cord circuit at said A operators position provided with a supervisory signal. manual means for extending said cord circuit to a telephone line. on the initiation of a call thereovcr, means responsive to said extension :tor connecting said telephone set to said cord circuit, means controlled from said A. operators position for automatically selecting an idle trunk ter1niouting at a B operations position, means operating responsive to raid selection tor dis connecting said opcrators telephone set "from said A cord circuit and for connecting it to said selected trunk, other means rcsponsive to the selecti n ot raid trunk tor connecting said B opcralors telephone set to said selected trunk whereby said A. opcrators telephone set and said 13 operators telephone set are telephonically connected togctlu-n' over said trunk, means for connecting the cord circuit to the selected trunk, means for connecting said trunk to the Wanted tclcphcuie line, means responsive to the connection o't said trunk to the Wanted telephone line for placing said single ringing key in operative relation to the sclccted trunk to the exclusion of the other trunks, ineans controlled by said common key for selectively applying ringing current to the Wanted telephone line, means controlled over said Wanted telephone line for disconnecting the signaling current, and means controlled from said Wanted telephone line over the selected trunk for op erating said supervisory signal.

(3. In a telephone exchange system, a calling line, a pluralitv of cord circuits each heing provided with an answering and a calling plug, an operatofis telephone set, means responsive to the connection of one of said answering plugs to said line for con nccting said operators telephone set to one of said cord circuits, a group of trunk circuits. a key common to said cord circuits and to said trunk circuits, and means responsive to the actuation of said key for disconnect; ing said oporators telephone set from said cord circuit and for connecting said opcr ators telephone set to one of said trunk circuits.

T. In a telephone exchange system, a call ing line, a plurality of. cord circuits each heing provided with an answering and a calling plug, an oporatofis telephone set, means responsive to the connection 01 one o i. said answering plugs, to said line for connecting said operators telephone set to one of? said cord circuits, a group of trunk circuits. a key common to said cord circuits and to said trunk circuits, means responsive to the actuation oi said key for disconnecting said u)eratois telephone set; from said cord circuit and for connecting said operatofs telephone set to one. of said trunk circuits, and means for thereafter connecting said cord circuit to said trunk circuit.

8. In a telephone system, an A opcrators position, a B operators position, telephone lines terminating at each of said positions, a plurality of trunks, serving to intercom nect said A and B operators positions, an operators telephone set at each of said A.

and B operators positions, means including automatic switching devices for selecting a trunk for use and for connecting said A operators telephone set thereto, a cord circuit for interconnecting a calling telephone line at the A operators position with the selected one of said trunks, means responsive to the connection of said cord circuit to a calling telephone line for connecting said A operators telephone set thereto, means responsive to the connection of said cord circuit to the selected one of said trunks for connecting said B operators telephone set thereto, and means responsive to the connection of said trunk to one of said telephone lines at said B operators position for dis connecting said B operators set from said trunk.

9. In a telephone system, an A operators position,-a B operators position, telephone lines terminating at each of said positions, a plurality oi trunks Serving to interconnect said A and B operators positions, an operators telephone set at each of said A and B operators positions, meansgfor selecting a trunk for use, a cord circuit for interconnecting the calling telephone line at the A operators position with any of said trunks, means responsive to the connection of said cord circuit to a calling telephone line for connecting said A operators telephone set thereto, means responsive to the selection of an idle one of said trunks for disconnecting said A operators telephone set from the calling telephone line, means responsive to the connection of said cord circuit to the selected one of said trunks for connecting said B operators telephone set thereto, and means responsive to the connection of said runk to one of said telephone lines at said B operators position for disconnecting said B operators telephone set from said trunk.

10. In a telephone system, an A operators position, a B operators position, telephone lines terminating at each of said positions, a plurality of trunks serving to interconnect said A and B operators positions, an operators telephone set at each of said A and B operators positions, means'for selecting a trunk for use, a cord circuit for interconnecting a calling telephone line at the A operators positionwith the selected one of said trunks, means responsive to the connection of said cord circuit to a calling telephone line forconnecting said A operators telephone set thereto, means responsive to the connection of said cord circuit to the selected one of said trunks for connecting said B operators telephone set thereto, a key common to said B operators position, and means responsive to the operation of said key for disconnecting said B operators telephone set from said trunk.

11. In a telephone system an A operators position, a B operators position, telephone lines terminating at each of said positions,

an operators telephone set at each position,

a plurality of trunks for interconnecting said positions, a cord circuit at said A operators position provided with manual switches for connecting said cord circuit to a calling telephone line and to any selected trunk, automatic means responsive to the connection of said cord circuit to a calling telephone line for extending said A operators telephone set thereto, a key common to said trunks, a set of relays for each trunk, means including an allotter and said key for variably operating said sets of relays to select an idle trunk and to connect said A operators telephone set to said selected trunk, means for connecting said B operators set to said selected trunk, and means for connecting the selected trunk to a wanted telephone line.

12. In a telephone system an A operators position, a B operators position, telephone lines terminating at each of said positions, an operators telephone set at each position, a plurality of trunks for interconnecting said positions, a cord circuit at said A operators position provided with manual switches for connecting said cord circuit to a calling telephone line and to any selected trunk, automatic means responsive to the connection of said cord circuit to a calling telephone line for extending said A operators telephone set thereto, a key common to said trunks, a plurality of group-selectin and unit-selecting relays common to said trunks, means including an extended starter wire circuit and said key for operating certain of said relays to select an idle trunk and to connect said A operators telephone set to said selected trunk, means for connecting said B operators telephone set to said selected trunk, and means for connecting the selected trunk to a wanted telephone line.

In witness whereof, I hereunto subscribe my name this 25th day of July, A. D. 19%.

VVINFRED T. POWELL. 

